In this paper we examined the electrical and optical properties of a new composite device containing layers of a nematic liquid crystal and cellulose derivative. Using the thermally stimulated depolarization Current (TSDC) method we obtained information regarding the conduction mechanism, the activation energy, and the pre-exponential frequency factor in the Arrhenius diagrams. The optical transmission is slightly dependent on the polarization field, and the thermal switch behavior was obtained at the nematic-isotrop transition. When a.c. voltage is applied to the sample, the optical transmission depends strongly on the field amplitude, and a very good contrast is obtained.